【 jpa的模糊查询，条件查询，分页】
做项目需要进行该项操作 查询相关资料没有太过明白的讲解， 查询了接近的三份资料总结出较为完美的分页（具体的东西不懂只能实现功能）
先是实体类
@Data
@Entity
public class Goods implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer gid;
private String gname;
private Integer price;
private Integer status;
private String des;
private String photo;
private Integer discount;
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name="tid")
private GoodsType goodsType;
}
------------------------------
@Data
@Entity
public class GoodsType implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer tid;
private String tname;
}
再是dao层
public interface GoodsDao extends JpaRepository<Goods,Integer> {
//进行分页的方法
Page<Goods> findAll(Specification<Goods> specification, Pageable pageable);
//不进行分页的方法
List<Goods> findAll(Specification<Goods> specification);
}
最后是service层
@Component
public class Xxxx {
@Resource
private GoodsDao goodsDao;
//pageNo：页数 pageSize：条目数 gname：对名字进行模糊查询 goodsType：商品类型
public List<Goods> queryFlows(int pageNo, int pageSize, String gname, GoodsType goodsType) {
List<Goods> result = null;
Specification<Goods> specification=new Specification<Goods>() {
@Override
public Predicate toPredicate(Root<Goods> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
List<Predicate> predicates=new ArrayList<Predicate>(10);
if(gname!=null){
predicates.add(criteriaBuilder.like(root.get("gname"),"%"+gname+"%"));
}
if(goodsType!=null){
predicates.add(criteriaBuilder.equal(root.get("goodsType").as(GoodsType.class),goodsType));
}
return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
}
};
try {
//进行分页的判断
if (pageNo == 0 && pageSize == 0) {
result = goodsDao.findAll(specification);
} else {
result = goodsDao.findAll(specification, PageRequest.of(pageNo - 1, pageSize)).getContent();
}
} catch (Exception e) {
e.printStackTrace();
}
return result;
}
}
最后进行测试
@SpringBootTest
public class MyTest {
@Resource
private Xxxx xxxx;
@Resource
private GoodsTypeDao goodsTypeDao;
@Resource
private GoodsDao goodsDao;
@Test
public void xxxx(){
GoodsType goodsType=goodsTypeDao.findById(1).get();
System.out.println(this.xxxx.queryFlows(1,5,"米",goodsType));
}
}
